24 Pieces Oki, Okidata Microline ML 420, 421, 490, 491, 720, 790, ML420, ML421, ML490, ML491, ML720, ML790 High Capacity, with the extended ink tank, Compatible Seamless Ribbons. These generic ribbons are similar to OEM 42377801 and designed to fit the 420 and 490 series dot matrix printers